I've thought about joining the y. How does their child care work? Do they have an age range? Does is cost extra?

Age range is I think 3m- until 8 yrs ( I believe). No extra cost. Mine all have a separate area for the little ones. You just sign them in, let the kids play and sign them out. The childcare ( at least at my gyms) are in big glass rooms, very visible. They close our childcare at a certain ratio of kids to providers- so that is nice otherwise it can get crazy in there.